Rear Differential Fill Plug seized trailblazer 2007 4.2L

Status
Not open for further replies.
Joined
Jun 7, 2016
Messages
275
Location
Toronto
Hey,

I need to remove the rear differential fill plug but it's seized in, and is now rounded off even after using the proper plug remover tool.
I cleaned, wire brushed it, spray lube, torched it and put a [censored] of a lot of torque on it to get it out but it didn't budge, eventually rounding it off.

Since I don't have a welder I decided I'm going to drill the thing out and use a left extractor tool.

But I can't find a replacement anywhere online it's a 3/4 thread.

I believe it's the GM 8 inch diff.

I was thinking of using an alternative brass pipe plug such as this: http://a.co/d/gyg8V8J as a viable replacement option.

Any recommendations?
 
Originally Posted by spasm3
Is the fill plug on the axle cover or on the side of the rear end?


side of the rear end.
 
3/4 inch npt is common in plumbing. Water heater plug are 3/4 inch. Maybe a local plumbing store.
 
Bolt thread is different from pipe thread though.
But as a fill plug, it may work.
 
Last edited:
I have the same issue on my avalanche, i got a replacement cover with a fill bolt, easier than drilling and getting dirt and filings in the rear end.
 
If its proud of the housing try using a chisel to knock it around. Any GM dealer should have or be able to get that plug. Be careful using spiral extractors, they snap off easily.
 
This?

https://www.rockauto.com/en/catalog/chevrolet,2007,trailblazer,4.2l+l6,1433505,drivetrain,differential+cover+plug,14368
 
Is the plug leaking? If not here's a thought. If it has a removable cover you might be able to buy a replacement cover with a fill plug built into it. I did that many years ago with a one of the vehicles I owned. It might have been a Suburban.
 
spasm3 said:
See if this looks like it will fit.

https://www.carid.com/2007-chevy-tr...tial-cover-693045075.html?parentsubmodel[]=WHEEL+DRIVE|RWD+%28Rear+Wheel+Drive%29


thanks.

I don't think there is a diff cover for this one with a fill plug. it's a LSD full AWD. I think it's G86, not sure though as I haven't verified it exactly to model number. 10 bolt.

i had purchased a gasket before, this one: http://a.co/d/9YlsCqZ (same gasket pattern as in the link you sent for the cover), but it was a wrong one so I ended up making my own gasket.

pattern is more like this: http://a.co/d/4C0c63R
 
Last edited:
Originally Posted by mattwithcats
This?

https://www.rockauto.com/en/catalog/chevrolet,2007,trailblazer,4.2l+l6,1433505,drivetrain,differential+cover+plug,14368



no, that's for the front differential.

that one came out easy.
 
Originally Posted by Trav
If its proud of the housing try using a chisel to knock it around. Any GM dealer should have or be able to get that plug. Be careful using spiral extractors, they snap off easily.



Tried the chisel before, I've taken bolts like that off before, but in this case, pieces of the bolt just fly off and it doesn't budge. and nowhere else to grip.
 
probably a dumb idea, but what if I put some epoxy in the plug bolt hole and put the extension inside and let it dry?
 
Last edited:
Should be able to find a cheap cover with a fill or a fancy G2 that has drain, fill, and oil level port ...
 
Try this first. Can you get a good onto the head of the plug. Give it several whacks then try the Allen socket. It should need a light tap to bottom in the socket. This technique works more times than not.
 
Originally Posted by andyd
Try this first. Can you get a good onto the head of the plug. Give it several whacks then try the Allen socket. It should need a light tap to bottom in the socket. This technique works more times than not.



I tried with allen key before as well. I tapped it hard as well. after lots of torque it eventually rounded off as well.

it's rounded off now doesn't matter what I put in there.

honestly this is rust belt here, this is probably an unusual circumstance to many people that such a thing can cause so much trouble.

I'll probably need to invest in a welder and learn to weld. may as well.
 
btw for anyone that is in similar circumstance.

I filled the differential with new oil through the overfill plug.

but it's a messy pain, to be quite honest. and won't be as accurate.


the overfill hose is long, so I cut it to leave a couple of inches near the diff, then pour the new oil in that way.

then I attached a little extension to join the cut hose back and used tiny hose clamps.

this works, but I would still like to take out the fill plug. it bothers me.
 
Status
Not open for further replies.
Back
Top